[Android] [Unity 6.2] Could not get unknown property 'unity.androidNdkPath' for project ':unityLibrary'

[timbotimbo]

Describe the bug
When using Unity 6000.2.0 with Android, you will get the following error:

FAILURE: Build failed with an exception.

* Where:
Build file 'C:\<path>\example\android\unityLibrary\build.gradle' line: 130

* What went wrong:
Execution failed for task ':unityLibrary:buildIl2Cpp'.
> Could not get unknown property 'unity.androidNdkPath' for project ':unityLibrary' of type org.gradle.api.Project.

* Try:
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.
> Get more help at https://help.gradle.org.

BUILD FAILED in 2s
Running Gradle task 'assembleRelease'...                            3.6s
Gradle task assembleRelease failed with exit code 1

To Reproduce

1. Use the Unity 6000 branch or flutter_unity_widget_2 to handle Unity 6 support.
2. Export Android using Unity 6000.2.0 or newer.
3. Attempt to run or build Flutter

More Context
Unity has changed the way they use NDK and SDK directories in unityLibrary/build.gradle.

Unity 2022.3/6000.0/6000.1 use android.ndkDirectory.
Unity 6000.2.0 uses unity.androidNdkPath and unity.androidSdkPath.

- commandLineArgs.add("--tool-chain-path=${android.ndkDirectory}")
+ commandLineArgs.add("--tool-chain-path=" + getProperty("unity.androidNdkPath"))

-    exec {
-       executable "${workingDir}/src/main/Il2CppOutputProject/IL2CPP/build/deploy/il2cpp${executableExtension}"
-        args commandLineArgs
-        environment "ANDROID_SDK_ROOT", getSdkDir()
-    }

+  def command =  "${workingDir}/src/main/Il2CppOutputProject/IL2CPP/build/deploy/il2cpp${executableExtension}";
+    execCommand(workingDir, [command, *commandLineArgs], [
+       "ANDROID_SDK_ROOT": getProperty("unity.androidSdkPath"),
+       "ANDROID_NDK_ROOT": getProperty("unity.androidNdkPath"),
+       "NDK_ROOT": getProperty("unity.androidNdkPath"),
+       "ANDROID_NDK_HOME": getProperty("unity.androidNdkPath"),
+    ])

These unity. properties are defined in gradle.properties in the Unity output.
Example of gradle.properties.

org.gradle.jvmargs=-Xmx4096M
org.gradle.parallel=true
unityStreamingAssets=
unityTemplateVersion=20
unityProjectPath=<path>flutter-unity-view-widget-flutter_unity_widget_2-6000/example/unity/DemoApp
unity.projectPath=<path>flutter-unity-view-widget-flutter_unity_widget_2-6000/example/unity/DemoApp
unity.debugSymbolLevel=none
unity.buildToolsVersion=34.0.0
unity.minSdkVersion=24
unity.targetSdkVersion=34
unity.compileSdkVersion=34
unity.applicationId=com.example.flutterunitywidget
unity.abiFilters=armeabi-v7a,arm64-v8a
unity.versionCode=1
unity.versionName=0.1
unity.namespace=com.example.flutterunitywidget
unity.agpVersion=8.7.2
unity.androidSdkPath=C:/Program Files/Unity/Hub/Editor/6000.2.0f1/Editor/Data/PlaybackEngines/AndroidPlayer/SDK
unity.androidNdkPath=C:/Program Files/Unity/Hub/Editor/6000.2.0f1/Editor/Data/PlaybackEngines/AndroidPlayer/NDK
unity.androidNdkVersion=27.2.12479018
unity.jdkPath=C:/Program Files/Unity/Hub/Editor/6000.2.0f1/Editor/Data/PlaybackEngines/AndroidPlayer/OpenJDK
unity.javaCompatabilityVersion=VERSION_17
unity.installInBuildFolder=false
android.useAndroidX=true
android.enableJetifier=true
android.bundle.includeNativeDebugMetadata=false
org.gradle.welcome=never

Fix

The easiest fix seems to be to copy Unity's gradle.properties file during the export.

FlutterUnityIntegration/editor/build.cs around line 250.

// private static void DoBuildAndroid

	Copy(buildPath, AndroidExportPath);

	// Unity 6000 shared folder
	string sharedPath = Path.Combine(APKPath, "shared");
	if (Directory.Exists(sharedPath)) 
	{
		Copy(sharedPath, Path.Combine(AndroidExportPath, "shared"));
	}

+   // Unity 6.2 requires unity.androidNdkPath and unity.androidSdkPath from gradle.properties.
+   File.Copy(Path.Combine(APKPath, "gradle.properties"), Path.Combine(AndroidExportPath, "gradle.properties"), true);

	// Modify build.gradle
	ModifyAndroidGradle(isPlugin);

	if(isPlugin)
	{
		SetupAndroidProjectForPlugin();
	} else
	{
		SetupAndroidProject();
	}

Alternatively you could define your own values in the android/gradle.properties of your Flutter project.

unity.androidSdkPath=
unity.androidNdkPath=

[thanon-dev]

Thankssssss so much <3
it worked on set FlutterUnityIntegration/editor/build.cs